Circuit breaker



6 Sheets-Sheet l M. J. LEWIS CIRCUIT BREAKER n lNvNToR Myair/:ZZ @a/5* ATTORNEYS original Filed oct. 17. 1947 April 7, 1953 M. J. LEWIS 2,634,347

CIRCUIT BREAKER original Filed oct. 17. 19217 e sheets-sheet 2 N Nk r,

INVENTOR piril '7; 1953" Original Filed Oct. 1'7. 1947 M. J. I Ewls 2,634,347

CIRCUIT BREAKER 6 Sheets-Sheet 5 N V EN TOR. @ya /vQea/,w

April 7, 1953 M. J. I Ewls 2,634,347

CIRCUIT BREAKER Original Filed Oct. 17. 1947 6 Sheets-sheet 4 I'lll April 7, 1953 M. J. LEWIS 2,634,347

CIRCUIT BREAKER original Filed oct. 17. 1947 6 Sheets-Sheet 5 XNVENTOR April 7, 1953 M J. LEWIS 2,634,347

CIRCUIT BREAKER 6 Sheets-Sheet 6 INVENTOR. jZgN/Q-eaa. BY

ATTORNEYS Patented Apr. 7, 1953 CIRCUIT BREAKER Morgan J. Lewis, Philadelphia, Pa.

Original application October 17, 1947, Serial No.

780,553, now Patent No. 2,620,417, dated December 2, 1952. Divided and this November 6, 1951, Serial No. 255,000

1 Claim.

My invention relates to electric contact making and breaking devices, particularly of the character which provide automatic quick release in case of overload or short circuit, and are commonly known as circuit breakers.

A purpose of the invention is to make the interconnecting parts for releasing and restoring the breaker more reliable and inexpensive in construction.

' A further purpose is to guide the end of the toggle breaking arm remote from the pivot of the releasing plate as later explained.

A further purpose is to guide the automatic releasing arm of the releasing plate.

Further purposes appear in the specification and in the claim.

In the drawings I have chosen to illustrate one only of the numerous embodiments in which my invention may appear, choosing the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

Figure 1 is a fragmentary top plan view of my improved circuit breaker, eliminating the housing.

Figure 2 is a section of Figure l on the line 2-2, breaking away one end of the outer housing.

Figure 3 is a section corresponding to Figure 2 showing only the switch in the position at which releasebegins.

Figure 4 is a view corresponding te Figure 3 showing the switch fully open.

, Figure 5 is an exploded fragmentary perspective showing the toggle and contacts.

Figure 6 is an enlarged detail longitudinal section through the movable contacts.

Figures 7, 8 and 9 are diagrammatic enlarged side elevations showing the steps in closing the contacts.

Figure 10 is a sectional perspective of the release mechanism.

Figure 11 is a perspective of the main supporting bracket.

Figure 12 is a detail perspective of the thermostatic elements and magnetic armature.

Describing in illustration but not in limitation and referring to the drawings:

The present application is a division of my U. S. patent application, Serial No. 780,553, led October 17, 1947, for Circuit Breaker which has become U. S. Patent No. 2,620,417, issued December 2, 1952.

The present subject matter is a further development of my U. S. Patent No. 1,888,559, dated November 22, 1932, for Electric Switch. Insofar application as the construction and operation of the present device is the same as that of my prior patent, I will describe it generally and refer those interested to my patent for further details.

In the prior art, on a dead short circuit or other similar condition circuit breakers for example of the type of my Patent No. 1,888,559 have in some cases suiiered serious damage, due to the fact that the current was not reduced rapidly enough during the iirst part of the opening movement of the contacts, so that damage was in some cases done to the circuit breaker itself. This condition was in part due to the character of contacts used in the prior art device, and the fact that during the opening of the breaker the current was not cut down sufliciently rapidly when the contacts were just beginning to open, partly open or just completely open.

The damage caused to the breaker in some cases took the form of burning out the thermostatic elements or alternatively of burning out the electromagnetic coils or both. While these injuries to the breaker could of course be repaired they did place the equipment out of service until a repair was completed and were very annoying.

The present invention represents an improvement over the prior art in avoiding this diiiiculty by assuring that even on a dead short circuit the reduction in current through the breaker will be so rapid that not only will the breaker protect the load and the generation system, but it will of course adquately protect itself. The present invention, therefore, is especially well suited to provide protection of electromagnetic and thermostatic elements of a breakerY during the opening of the breaker. Y

The switch of the present invention comprises an outer metallic housing 20 of general box formation, which is closed at the top by an outer cover 2l suitably fastened thereto, as by screws and seals ordinarily used in electrical work (not shown), and outwardly deformed at 22 to permit motion of the switch. Within the housing 20 and suitably bolted at 23 to the rear or bottom thereof, I provide an insulating base 24, preferably of electrical procelain or the like. At one end the base is formed to provide a terminal block 25 with suitable separating ribs 26 spacing terminals 21 connected to the line, and terminals 28 connected to the load. The ribs 26 terminate short of ribs 30 for mounting the switch, leaving a space 3| extending across the base and engaging and locking the lower end of an insulating end wall 32 (Figure 2) of an inner cover 33 which encloses the switch proper while permitting `access to the terminal block. The upper and suitably metallic portion 34 of the inner cover is joined to the insulating end wall 32 as by rivets 32', shrouded by washers 322 of rubber or the like. The inner cover is deformed at 315 to t within deformed portion 22 on the outer cover.

It Willthus be evident that the inner cover 33 is suitably secured (as by screws and seals not shown) and prevents unauthorized access to the Y switch while nevertheless permitting access to the terminal block for connection or disconnection.

The switch proper is mounted on a'channelshaped bracket 34 suitably fastened to the in sulating base at 35 and insulatedjfrom thejelectrical parts (the bracket is seen more in detail in Figure 11). The bracket has a suitable base 35, side walls 3l' and a cover 38 having projections t for protecting the biasing spring later to be described, and guiding the upper ends of the releasing plates. at the endremote from the switch there is also a V'tongue il for protecting another biasing spring.

From the bracket, operating mechanism manipulates switch blades l2 and llpivoted at on conducting standards'i. The standards are suitably mounted on'the insulating base and interconnected to the load through thermostat supports e mounted on the base, metallic thermostatic strips til vertically supported thereon near the bottomsof the strips`,then through down wardly extending metallic thermostatic strips 48 joined at the top to'strips Lthrough support 5G on which the strip d'8 is mounted, through magnet coilll and through terminal strip 28. The thermostatic strips 'di and 48 are positione'd s'o'as'to move'towardA the magnet coils with increased temperatures as later explained.

The switchV blades i2 and 5 3 are interconnected byan insulating bar'g extending from sideA to side Ytoward theouter ends and suitably fastened to the Yswitchfblades as'-at"53 l(Figure 5). y y y The'covoperating Yixed contacts comprise elongated* stripsiliv ofv copper or the like Vsuitably mounted-onA the base and ,interconnected with the line by bu's'bars, preierably carried in recesses beneathvthe base'. e Each of the xed contacts is lgenerally bentaway from the base at 5B and'fabove this pointjis' inclined with respect to theba'se and withrespect toanv imaginary line between the switch 'p ivot 4 andv any point on the VVfixed contact. jllfiusl there is in the form shown` anV outer, less vsteeply inclined portion 5l, nearethe end of Vtlredfixed, contact remote fromthe pivot of the switch'bladeaiid'lan intermediate more steeply inclined portiQil ,53 as best seen'in Figures '7, 8 'lndQ-.T ',QOYn the outer end of each switch blade isamovable' contact liuelectri'cally connected to the blade 'alsl by 'an electrically7 conducting spacer 5 l screwed to the blade att? and' riveted to the contactar. 53 v(Figure`v 6). Rotation is prevented by notch 62 engaging the blad@ The movable contact'isspecially constructed so as to prevent fouling. 'With this 'object itis constructedyof a' number of sepa-rateY contactpads 'preferably in` the form of resilient strips of spring material such as spring bronze, spring 4brass or beryllium copper, with or without contactblocks. The pads are-preferably arranged as overlapping leaves so that theyrwill'contact the fixed contact at la plurality of pointsand-preferablysuccessively. The fo'rwardmost pad as shown is made up of two leaves 54 and 55 Ymountir'iga metallic contactblock t5 at the outerlfends, Tand in-closing the switch making contact with the outer extremity of the fixed contact 54 before any other contact pad has made contact. Thus if any arcing is likely to take place, on the making or on the breaking, it will take place in the region El of Figure '7, since in this position no other portion of the contact pads will be closely adjacent'to the ixed contact. Thus arcing and'pitting over the portion 58 of the fixed contact is prevented.

rThe successive contact in closing and the suc- Y vcessive breaking in opening will be accomplished by other contact pads, suitably the pad 58 which is-"next to make contact in closing as shown by Figure 8,-backed up by the pad above at 1U. An instantafter Contact is made by the pad 68, contact is made by the next pad Eil which is somewhat shorter, and-nally contact is made by the last pad l2. The pads 58, 'l and 'il suitably have reverse'bends on their outer ends to increase the current carrying capacity slightly. Of course any suitable number of Contact pads arranged in echelon may be'used.

It will be evident, therefore, that in closing the contacts of each switch blade, contact will rst be made by the outermost pad and then successively by the pads whose outer ends arenearer to the-pivot, Whereasin opening the reverse will take place, and the pads whose outer ends are nearer to the pivot will break contact while current is rstill flowing through the outermost pad and therefore while there is little or'no tendency to arc and spoil the-'contact surface at 58.

Whereas in the present invention anyl suitable number of switch vpoles may be'used, Ivhave illustrated in this ca'se a two pole switch, but it willbe understood that the invention isin no way restricted toa switch of thisty'pe.V

Each of the xed contacts yis surrounded on both sides by an ar'cing shoe 13, suitably'of steel, which is preferably a U-'shaped member having a base it, upstandi-ng sides l5, arin'g outer ends i5 and inclined outer edges il which conform genera.l1ytothe slope of 'the xed contact atY 5l and 55; ltwillthus be Vevidentthat as themovable contacts separate they are laterally within arcdistance ofv the arci'n'g'shoe's at each side, whereas the xedcont'act is likewise at eachrside within ar'cirg distance of the arcing shoes. The arcingfshoes are, however, preferably electrically connected to the fixed contacts, and thereforeiit will be evident that the a'rcing will primarily be between the movable contact and the'ar'cir'igv shoes, and will be finally broken' by the outwardly flaring edges of the shoes. It is important to note, however, that the inclined character of the outer edges of the shoes tends to space the contact pads substantially widely from' the arcingshoes ais the movable contact moves outwardly, butthe contact block 56 is made slightly wider as shown in 'Figures-1 and 5,-softhat mosrorf the ama; win

take place on the contact block, /pr'oteoting'the 'sides of the contact pads.

Vthe switch Vclosingfpr'isition by a torsion spring iii, one end of 'which engages the housing.

Throughout the'portin of the crank which' contacts the opera-ting lparts it is surrounded by insulating sleeve 82. The crank extends through -Van elongated slot t3 ofal channel-shaped toggle member til *which makes toggle 'pivotal connecztimat tarzan 'semmai-shaped forwardftoggie member-96 which has pivotal kconnection at 81 with a longitudinal slot 88 of a saddle 90 mounted near the middle on the insulating cross connection 52 of the switch. The toggle is spring urged toward straightening by a torsion spring 9| suitably surrounding the pivot 85.

` T sustain the pressure in closing the switch and avoid breaking through the insulation 82, a socket 92 is provided at the end of slot 83 toward the fixed contacts.

The switch blades are biased toward opening by a tension spring 93 connecting from a spring abutment 94 on the bracket 35 to a spring engaging hook 95 on the insulating bar 52.

The switch is secured in closed position by a latch 90 (one for each pole) pivotally mounted at 91 on the bracket and spring urged toward latching position by a compression spring 98 engaging a lever end |00 near the base of the latch; The latch is limited against moving rearwardly beyond its latching position through engagement of projections |01 with the base of .the bracket.

The switch may be opened manually by pulling on the handle in such a way as to operate the crank 80 counterclockwise in Figure 2, pulling on the toggle and moving the pivot B1 in the slot ,88 toward the switch blade pivot so as to withdraw the pivot 81 from engagement beneath the latch 96 as in my patent above referred to.

The switch may likewise be manually closed by moving the handle in the direction to swing the crank clockwise in Figure 2, forcing the movable contacts into clamping engagement with the fixed contacts, forcing the pivot 81 forward in the slot 88 and permitting it to deflect the latch 96 and be held beneath the latch as shown in Figure 2.

Automatic release or the latch 96 is accomplished by a releasing plate |02 as best seen in Figure 10. One releasing plate is provided for each switch blade, and the releasing plate is conveniently pivoted at 91 on the latch pivot, suitably on the inside of the corresponding latch, the releasing plates being separated by a spacer |03 (Figure 10). Each releasing plate has a latch releasing arm |04 extending away from the base and adapted to engage a cross connection |05 between the latches, which, with a top cross connection |06, assures that the latches move together. The releasing plate also has a longitudinal extending body |01 (Figure 10) from which projects away from the base a toggle breaking arm |08, adapted to engage the toggle pivot 85. Also at the rearward end is the automatic releasing arm l0 which projects outwardly through an opening in the bracket to engage under an automatic releasing dog (best seen in Figure which is mounted on the thermostatic arms 41 and 8 in the position opposite to the coil 5|. The upper joining ends of the thermostatic arms 41 and 48 are preferably insulated on either side at I2 and |3 to permit mounting the dog ||0 without connecting it into the electrical circuit.

On the side of the upper ends of the thermostatic arms 41 and 48 toward the coil is mounted an armature I4 of suitable magnetic susceptible material, such as low carbon steel. In the prior art when an unbroken disc armature was employed, considerable difculty was encountered with alternating current hum when the overload approached a condition close to that for kicking out the circuit breaker. I have discovered that this difliculty may be overcome by inserting an air gap or slot |'i5 extending radially through the armature from the outer circumference to a point adjacent to the interior as best seen in Figure 12. It has been found that by employing the slot described it is possible to maintain sharp overload release and nevertheless operate without objectionable noise for long periods at overloads slightly below the release point. The coils 5| are provided with suitable cores and pole pieces I6 to cooperate with the armature.

rlhe toggle breaking projection |08 of the releasing plate may be conveniently guided by the side of one of the protecting prongs G0 as seen at ||1, and the base of the automatic releasing arm H0 is suitably guided by the side of the tongue 4| at |18 (Figure 10). Each releasing plate is biased toward release position by a tension spring |20 extending from the abutment 94 to a spring anchor 2| on the rearward edge of each releasing plate.

In operation the switch of the present invention will frequently be used to replace the main fuses on a volt alternating or direct current supply to a house, or the like, although of course it may be used in numerous other applications, as for example, to provide a circuit breaker for motors or other load equipment at any suitable voltage.

The device can be opened and closed like an ordinary switch to turn the current off or on m-anually simply by operating the handle. The toggle will remain stiff and the contacts will be forced closed, first bringing the contact blocks 65 into engagement with the portions 51 of the fixed contacts and then successively bringing the individual resilient metallic contact pads into engagement with the portions 58. In breaking the circuit the reverse sequence will be followed, the contact at each block $6 being the last broken, and the arcing shoes having diverging edges terminating on an incline similar to that of the iixed contacts and that of the movable contacts at that position, breaking the arc.

When the device is closed automatic operation will begin, since the current will pass through the thermostatic arms 41 and 48 which are biased toward opening of the automatic release by moving the release dog away from engagement with the automatic releasing arm ||0 (Figure 10), thus protecting against long continued overloads slightly above the proper value, and also because the current is owing through coil 5|, which by pulling on the armature ||4 is tending to pull the automatic release dog ||0 out from engagement with the arm ||0. There is enough time lag to prevent release on a momentary somewhat excessive current iiow incident to starting a motor or the like.

The thermostatic arms are not used to open the switch but to keep the coils from opening the switch on momentary overloads such as starting motors. The heavier the overload or short, the more the coil is effective and the less the thermostatic arms are eifective, so that as the thermostatic arms heat up they move the armature nearer to the coil.

Should an excessive overload or a short circuit occur, the automatic release dog will move out from engagement with the automatic releasing arm ||0 and the corresponding releasing plate |02 will swing pivotally under the action of its biasing spring |20. This will cause the arm |04 to move the latch 96 to unlatching position and will cause the toggle breaking projection |08 to break the toggle as shown in Fig- 7 ure 3, causing the switch to open under the action of the switch biasing spring 93 as shown in Figure 4. As the switch opens its movable contacts break in the order referred to and the arcing shoes break the arc.

The switch is nowv reset. manually, after repairing the diiculty in the circuit, by moving the handle in the direction to pull the crank counterclockwise in Figures 2, 3 and 4, so that the toggle breaking projection |08 is engaged at 122 with the anchorage 9G on the insulating cross bar 52. This engagement is shown in Figure 4, although the crank is no longer in the limited counterclockwise position. This restores. the releasing plate to its engagement with theautomatic release dog as shown in Figure 1 0, preu pared for further automatic release. rfile switch handle is then moved in the opposite direction to carry the toggle forward and close the switch as in the previously described manual operation, restoring the condition shown in Figure 2. Should the device nevertheless encounter a further short circuit or excessive overload when it is manually closed, it will kick out notwithstanding the pressure on the handle due to the breaking of the toggle and the release of the latch.

An important function of the special contacts and arcing horns in accordance with the invention. is that the thermostatic elements and/or electromagnets of the breaker are adequately protected against damage during the opening, due to the fact that the current incident to a short circuit or other greatly abnormal current flow is cut off too rapidly to do permanent damage.

It will be evident of course that the present invention nds its best expression in circuit breakers, but it also may be applied to great advantage. in switch mechanism of other types.

In view of my invention and disclosure variations and modifications to meet individual. whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of. the benefits of my invention without copying the structure shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claim.

Having thus described my invention what I claim as new and desirev to secure. by Letters Patentis:

In a circuit breaker.. a channel-shaped bracket. a latch pivoted on the forward end of the bracket, spring means to urge the latch toward latching position, a movable switch blade. a. pivot for the movable switch blade, spring means for biasing the movable switch blade toward opening, a movable contact on the end-of. the movable switch blade, a fixed. contact cooperating with the movable contact, a toggle for closing the switch blade, an automatic releasing dog adjacent the rearward end of the bracket1 thermostatic arms supporting the automatic releasing. dog and tending to move it toward opening position as they become more heated, an armature mounted with the automatic releasing dog, an electromagnet urging the armature torward the release position of the automatic releasing dog and a releasing plate pivoted on the forward end of the bracket, spring urged toward opening position, having a releasing arm. which operates the latch in opening, having a toggle breaking projection which breaks the toggle in opening, having a. return abutment for engaging a part movable with the switch. blade for restoring to automatic release position and having an automatic releasing arm for retention by the automatic releasing dog, in combination with a projection on the bracket guiding the end of the toggle breaking arm remote from the pivot of the releasing plate and a tongue on the bracket guiding the automatic releasing arm of the releasing plate.

NIORG'AN J. LEWIS.

REFERENCES CITED The following references are of record in the file. of this patent:

UNITED' STATES PATENTS Number f N ame Bate 1,888,559- Lewis Nov. 22, i932 1,960,402 Wilckens May 29, 1934 

